Since the main thrust of this discussion centers on the matter of authority, I would assert that an examination of the development of other authority structures would be germane to the discussion.
The first authority and the basis for it are quite clearly spelled out in scripture.
(Revelation 4:11) 11 “You are worthy, Jehovah, even our God, to receive the glory and the honor and the power, because you created all things, and because of your will they existed and were created.”
He has delegated some of that authority.
(Matthew 28:18) 18 And Jesus approached and spoke to them, saying: “All authority has been given me in heaven and on the earth.
The first authority in human society is based on the family unit. Creation of these relationships hinged entirely on whether or not individuals chose to become part of such an arrangement. However, once they did, they were subject to that authority structure. While Jehovah instituted this arrangement, the expression of it has not remained constant throughout history. One example is the tolerance and regulation of polygamy.
(Ephesians 5:22-24) 22 Let wives be in subjection to their husbands as to the Lord, 23 because a husband is head of his wife as the Christ also is head of the congregation, he being a savior of [this] body. 24 In fact, as the congregation is in subjection to the Christ, so let wives also be to their husbands in everything.
(1 Corinthians 11:3) 3 But I want YOU to know that the head of every man is the Christ; in turn the head of a woman is the man; in turn the head of the Christ is God.
(Ephesians 6:1-2) 6 Children, be obedient to YOUR parents in union with [the] Lord, for this is righteous: 2 “Honor your father and [your] mother”; which is the first command with a promise:
As human society redeveloped after the flood, groups of humans formed themselves into larger societies, such as the patriarchal system, city states and eventually kingdoms, empires and nations. Jehovah at times made use of these human constructs.
(2 Chronicles 33:11) 11 Finally Jehovah brought against them the chiefs of the army that belonged to the king of As•syr´i•a, and so they captured Ma•nas´seh in the hollows and bound him with two fetters of copper and took him to Babylon.
I submit that for centuries it was vague as to what viewpoint a servant of Jehovah should have of these emerging authority structures, especially after the nation of Israel lost its special position. Paul clarified the correct viewpoint in Romans.
(Romans 13:1-7) 13 Let every soul be in subjection to the superior authorities, for there is no authority except by God; the existing authorities stand placed in their relative positions by God. 2 Therefore he who opposes the authority has taken a stand against the arrangement of God; those who have taken a stand against it will receive judgment to themselves. 3 For those ruling are an object of fear, not to the good deed, but to the bad. Do you, then, want to have no fear of the authority? Keep doing good, and you will have praise from it; 4 for it is God’s minister to you for your good. But if you are doing what is bad, be in fear: for it is not without purpose that it bears the sword; for it is God’s minister, an avenger to express wrath upon the one practicing what is bad. 5 There is therefore compelling reason for YOU people to be in subjection, not only on account of that wrath but also on account of [YOUR] conscience. 6 For that is why YOU are also paying taxes; for they are God’s public servants constantly serving this very purpose. 7 Render to all their dues, to him who [calls for] the tax, the tax; to him who [calls for] the tribute, the tribute; to him who [calls for] fear, such fear; to him who [calls for] honor, such honor.
Now the question arises as to how these governments evolved into superior authorities. In modern Western thought, it is generally theorized that a legitimate government can only exist with the permission of the governed. Is the US government a legitimate authority that we should be in subjection to from a scriptural perspective? If so, at what point did it attain this legitimacy? In most of human history, these superior authorities attained their positions through force, not permission. Still Paul considered them to be legitimate authorities and did not even preach against slavery.
The nation of Israel is a special case since they came into existence only through divine intervention. Even in this case humans were allowed to develop and modify the authority structures. Moses listened to Jethro when delegating some of his authority.
(Exodus 18:13-27) 13 And it came about on the next day that Moses sat down as usual to serve as judge for the people, and the people kept standing before Moses from the morning till the evening. 14 And Moses’ father-in-law got to see all that he was doing for the people. So he said: “What kind of business is this that you are doing for the people? Why do you alone continue sitting and all the people continue taking their stand before you from morning till evening?” 15 Then Moses said to his father-in-law: “Because the people keep coming to me to inquire of God. 16 In the event that they have a case arise, it must come to me and I must judge between the one party and the other, and I must make known the decisions of the [true] God and his laws.” 17 At this Moses’ father-in-law said to him: “It is not good the way you are doing. 18 You will surely wear out, both you and this people who are with you, because this business is too big a load for you. You are unable to do it by yourself. 19 Now listen to my voice. I shall advise you, and God will prove to be with you. You yourself serve as representative for the people before the [true] God, and you yourself must bring the cases to the [true] God. 20 And you must warn them of what the regulations and the laws are, and you must make known to them the way in which they should walk and the work that they should do. 21 But you yourself should select out of all the people capable men, fearing God, trustworthy men, hating unjust profit; and you must set these over them as chiefs over thousands, chiefs over hundreds, chiefs over fifties and chiefs over tens. 22 And they must judge the people on every proper occasion; and it must occur that every big case they will bring to you, but every small case they themselves will handle as judges. So make it lighter for yourself, and they must carry the load with you. 23 If you do this very thing, and God has commanded you, you will then certainly be able to stand it and, besides, this people will all come to their own place in peace.” 24 Immediately Moses listened to the voice of his father-in-law and did all that he had said. 25 And Moses proceeded to choose capable men out of all Israel and to give them positions as heads over the people, as chiefs of thousands, chiefs of hundreds, chiefs of fifties and chiefs of tens. 26 And they judged the people on every proper occasion. A hard case they would bring to Moses, but every small case they themselves would handle as judges. 27 After that Moses saw his father-in-law off, and he went his way to his land.
Later the nation would clamor for another modification by insisting on having a human king.
(1 Samuel 8:1-22) 8 And it came about that as soon as Samuel had grown old he made appointments of his sons as judges for Israel. 2 Now the name of his firstborn son happened to be Joel, and the name of his second A•bi´jah; they were judging in Be´er-she´ba. 3 And his sons did not walk in his ways, but they were inclined to follow unjust profit and would accept a bribe and pervert judgment. 4 In time all the older men of Israel collected themselves together and came to Samuel at Ra´mah 5 and said to him: “Look! You yourself have grown old, but your own sons have not walked in your ways. Now do appoint for us a king to judge us like all the nations.” 6 But the thing was bad in the eyes of Samuel inasmuch as they had said: “Do give us a king to judge us,” and Samuel began to pray to Jehovah. 7 Then Jehovah said to Samuel: “Listen to the voice of the people as respects all that they say to you; for it is not you whom they have rejected, but it is I whom they have rejected from being king over them. 8 In accord with all their doings that they have done from the day of my bringing them up out of Egypt until this day in that they kept leaving me and serving other gods, that is the way they are doing also to you. 9 And now listen to their voice. Only this, that you should solemnly warn them, and you must tell them the rightful due of the king who will reign over them.” 10 So Samuel said all the words of Jehovah to the people who were asking a king of him. 11 And he proceeded to say: “This will become the rightful due of the king that will reign over YOU: YOUR sons he will take and put them as his in his chariots and among his horsemen, and some will have to run before his chariots; 12 and to appoint for himself chiefs over thousands and chiefs over fifties, and [some] to do his plowing and to reap his harvest and to make his war instruments and his chariot instruments. 13 And YOUR daughters he will take for ointment mixers and cooks and bakers. 14 And YOUR fields and YOUR vineyards and YOUR olive groves, the best ones, he will take and actually give to his servants. 15 And of YOUR fields of seed and of YOUR vineyards he will take the tenth, and he will certainly give [them] to his court officials and his servants. 16 And YOUR menservants and YOUR maidservants and YOUR best herds, and YOUR asses he will take, and he will have to use them for his work. 17 Of YOUR flocks he will take the tenth, and YOU yourselves will become his as servants. 18 And YOU will certainly cry out in that day by reason of YOUR king, whom YOU have chosen for yourselves, but Jehovah will not answer YOU in that day.” 19 However, the people refused to listen to the voice of Samuel and said: “No, but a king is what will come to be over us. 20 And we must become, we also, like all the nations, and our king must judge us and go out before us and fight our battles.” 21 And Samuel gave a hearing to all the words of the people; then he spoke them in the ears of Jehovah. 22 And Jehovah proceeded to say to Samuel: “Listen to their voice, and you must cause a king to reign for them.” Accordingly Samuel said to the men of Israel: “Go each one to his city.”
Later it was said that the king sat on Jehovah’s throne. Does this imply that Jehovah acquiesced and used this institution?
(1 Chronicles 29:23) 23 And Sol´o•mon began to sit upon Jehovah’s throne as king in place of David his father and to make a success of it, and all the Israelites were obedient to him.
Other examples of the latitude given to Israel may be found in the establishment and observances of the Festival of Lots and the Festival of Dedication. A case previously mentioned is the Sanhedrin and Jesus did give counsel to be obedient to the Jewish leaders to some extent.
(Matthew 23:1-3) 23 Then Jesus spoke to the crowds and to his disciples, saying: 2 “The scribes and the Pharisees have seated themselves in the seat of Moses. 3 Therefore all the things they tell YOU, do and observe, but do not do according to their deeds, for they say but do not perform.
After Jesus’ death the 1st century congregations developed authority structures in the form of elders & ministerial servants or bishops & deacons or whatever they are labeled.
(Titus 1:5) 5 For this reason I left you in Crete, that you might correct the things that were defective and might make appointments of older men in city after city, as I gave you orders;
(Hebrews 13:17) 17 Be obedient to those who are taking the lead among YOU and be submissive, for they are keeping watch over YOUR souls as those who will render an account; that they may do this with joy and not with sighing, for this would be damaging to YOU.
Based on past history, if Jehovah has begun to gather a group of people to serve him, they would have a certain amount of latitude in developing their authority structures, including creating a GB in spite of the fact that one did not exist in the first century.
Summary: The point is that an authority structure does not have to be established through divine intervention in order to be legitimate. The Sanhedrin did have some legitimate authority notwithstanding the self-aggrandizing claims about their origin. The consistent pattern shown by those in authority is to abuse it. This pattern has held true in every human social structure, whether established by Jehovah or not. The pattern holds true even among JWs where apparently those in authority want us to be in absolute subjection to them in contrast to every other human authority which are quite correctly viewed as deserving only relative subjection.